KR20180133534A - A system, method, and computer program product for detecting defects in a target component manufactured using consistent modulation for a target component and a reference component - Google Patents

Abstract

A fabricated device is provided that has a consistent modulation between a target component and a reference component. The fabricated device comprises a target component with a first modulation. The fabricated device further comprises at least two reference components for a target component comprising a first reference component and a second reference component, wherein the first reference component and the second reference component each have a first modulation. There is also provided a system, method, and computer program product for detecting a defect in a target component manufactured using consistent modulation for a target component and a reference component nut.

Description

A system, method, and computer program product for detecting defects in a target component manufactured using consistent modulation for a target component and a reference component

This application claims the benefit of U.S. Provisional Application No. 62 / 331,567, filed May 4, 2016, which is hereby incorporated by reference in its entirety.

The present invention relates to the inspection of manufactured components, and more particularly to detecting defects in manufactured components.

Recently, a defect in a manufactured component (e.g., a wafer) can be detected by comparing the target component of the manufactured device against the reference component of the manufactured device. The inspection system accomplishes this by taking images of the target and reference components for comparison purposes. In particular, the step of detecting defects is often performed by two separate comparisons to produce two separate results, one between the target component and one of the reference components, and another comparison between the target component and the other one of the reference components . Any similarity between the two separate comparison results is generally used as an indicator of the defect in the target component.

1 of the prior art has a plurality of target components in a column 102 that are the same pattern modulated by different combinations of parameters (e.g., focus F and exposure E), respectively, And a plurality of reference components in columns 104 and 106, each positioned on either side of a column of columns 104 and 106, each of which is a nominal (i.e., unmodulated) version of the same pattern. Thus, for any particular one of the target components in the column 102, the reference component from the column 104 and the reference component from the column 106 may be used as a reference component for a particular target component (based on the box 108) Can be used for detection. Although the reference component is shown as being adjacent to the target component, it is not necessary in all cases. For example, in other wafer configurations, a reference component for any particular target component may be a component that is not necessarily contiguous but closest to a particular target component.

Unfortunately, conventional methods for performing the above-described defect detection include techniques for deriving imprecise results. For example, as described above, the target component is modulated to amplify the defect. This amplifies both defects and non-deficiencies in the target component. However, the reference component is traditionally nominal. Subsequently, modulating only the target component will display a similar structure of the target and reference components differently when there is virtually no defect. Thus, the number of traditionally identified defects may be too high, which limits the ability to discern actual defects from misidentified defects.

2 shows an example of the effect of the conventional defect detection method adopting the modulation of only the target component. In Fig. 2, as the modulation for the target component increases, the size of each part (including defects and non-defects) of the target component also increases, so that the target component and the reference component are distinguished for each part regardless of the actual defect. As shown, the different images obtained from the comparison in the higher modulation include further differences than the lower modulation. Existing patents disclosing the above prior art are described in U.S. Pat. Patent No. 8,213,704 and U.S. Pat. Patent No. 6,902,855, the disclosure of which is incorporated herein by reference in its entirety.

Accordingly, there is a need to address these and / or other problems associated with the prior art used for defect detection in fabricated components.

In one embodiment, a fabricated device is provided that has a consistent modulation between a target component and a reference component. The fabricated device comprises a target component with a first modulation. The fabricated device further comprises at least two reference components for a target component comprising a first reference component and a second reference component, wherein the first reference component and the second reference component each have a first modulation.

In another embodiment, a system, method, and computer program product are provided for detecting a defect in a target component manufactured using consistent modulation for a target component and a reference compo- nent. In use, a first image of a target component of the fabricated device is received, and the target component has a first modulation. Also, a second image of a first reference component of the fabricated device for the target component is received, and the first reference component has a first modulation. Also, a third image of a second reference component of the fabricated device for the target component is received, and the second reference component has a first modulation. Also, a first comparison of the first image and the second image is performed to produce a first result indicative of the difference between the first image and the second image, and the difference between the first image and the second image A second comparison of the first and third images is performed to produce a second result, and a third comparison between the first and second results is performed to detect defects in the target component.

Figure 1 shows an exemplary layout of a wafer according to the prior art.
Fig. 2 shows an example of the effect of the conventional defect detection method adopting the modulation of only the target component according to the prior art.
3A illustrates a block diagram illustrating one embodiment of a non-volatile computer readable medium including program instructions executable on a computer system to perform the one or more computer-implemented methods disclosed herein.
Figure 3B is a schematic diagram illustrating a side view of an embodiment of an inspection system configured to detect defects on the fabricated device.
4 illustrates a fabricated device with consistent modulation between a target component and a reference component, according to an embodiment.
5 illustrates a method for comparing a reference component with a target component that is consistently modulated for defect detection, in accordance with an embodiment.
Figure 6 illustrates a detected defect that is gradually removed in an increased modulation, in accordance with an embodiment.
Figure 7 illustrates statistics generated as a function of the number of defects detected in a pattern for different modulation, according to an embodiment.

The following discussion discloses a manufactured device having a consistent modulation between a target component and a reference component, as well as a system, method, and computer program product that compares a reference component with a target component that is consistently modulated to detect a defect . The system, method, and computer program product, including the various embodiments described below, may be implemented in any of a variety of ways (e.g., wafer inspection, reticle inspection, laser scanning inspection systems, etc.) And the like.

Additional embodiments are directed to non-volatile computer readable media for storing program instructions executable on a computer system to perform a computer implemented method for detecting a defect using a consistently modulated target component and a reference component. One such embodiment is shown in Figure 3A. 3A, computer readable medium 300 includes program instructions 302 executable on computer system 304. In one embodiment, The computer implemented method includes the steps of the method described below with reference to FIG. Computer-implemented methods by which program instructions may be executed may include any of the other operations described herein.

Program instructions 302 implementing the methods disclosed herein may be stored in computer readable media 300. [ The computer-readable medium may be a known magnetic or optical disk, or a storage medium such as magnetic tape or any other suitable non-volatile computer readable medium. Optionally, the computer readable medium 300 may be located within the computer system 304.

Program instructions may be implemented in any of a variety of ways, including, among others, procedural based, component based, and / or object oriented techniques. For example, program instructions may be implemented on demand, using ActiveX controls, C ++ objects, JavaBeans, Microsoft Foundation Classes ("MFC"), or other techniques or methods.

Computer system 304 may take a variety of forms, including personal computer systems, image computers, mainframe computer systems, workstations, network equipment, Internet equipment, or other devices. In general, the term "computer system" can be broadly defined to encompass any device having one or more processors executing instructions from a memory medium. Computer system 304 may include any suitable processor known in the art, such as a parallel processor. In addition, the computer system 304 may include a computer platform with high-speed processing and software, such as a stand-alone tool or a network-like tool.

A further embodiment relates to a system configured to detect defects on a fabricated device. One embodiment of such a system is shown in Figure 3B. The system includes an inspection system 305 configured to generate an output for a component to be fabricated on a wafer (or other device) configured in an embodiment as disclosed herein. The system also includes one or more computer systems configured to perform the operations described below with reference to FIG. One or more computer systems may be configured to perform operations in accordance with any of the embodiments disclosed herein. The computer system (s) and system may be configured to perform any of the other operations described herein, and may be configured as disclosed herein.

In the embodiment shown in Figure 3B, one of the computer systems is part of an electronic automation design (EDA) tool, and the inspection system and other computer systems are not part of the EDA tool. The computer system may include, for example, the computer system 304 described above with reference to FIG. For example, as shown in FIG. 3B, one of the computer systems may be a computer system 308 included in the EDA tool 306. The EDA tool 306 and the computer system 308 included in such a tool may include all commercially available EDA tools.

The inspection system 305 can be configured to generate an output for a component to be fabricated on a wafer by scanning the wafer with light and detecting light from the wafer during scanning. For example, as shown in FIG. 3B, the inspection system 305 includes a light source 320 that may include any suitable light source known in the art. The light from the light source may be directed to a beam splitter 318, which may be configured to direct light from the light source to the wafer 322. Light source 320 may be coupled to any other suitable element (not shown) such as one or more condenser lenses, collimating lenses, relay lenses, objectives, apertures, spectral filters, polarization components, As shown in FIG. 3B, the light may be directed to the wafer 322 at a normal incidence angle. However, the light can be directed to the wafer 322 at any suitable angle of incidence including nearly vertical and oblique incidence. Also, the light or a plurality of light beams may be directed to the wafer 322 sequentially or simultaneously at one or more incident angles. The inspection system 305 can be configured to scan the light onto the wafer 322 in any suitable manner.

The light from the wafer 322 may be focused and detected by one or more channels of the inspection system 305 during scanning. For example, light reflected from the wafer 322 at an angle close to the vertical (i.e., light regularly reflected when the angle of incidence is vertical) can pass through the beam splitter 318 to the lens 314. The lens 314 may comprise a refractive optical element as shown in FIG. 3B. The lens 314 may also include one or more refractive optical elements and / or one or more reflective optical elements. The light condensed by the lens 314 can be focused by the detector 312. [ Detector 312 may comprise any suitable detector known in the art, such as a charge coupled device (CCD) or other type of imaging detector. The detector 312 is configured to produce an output in response to the reflected light condensed by the lens 314. [ Thus, lens 314 and detector 312 form one channel of inspection system 305. This channel of inspection system 305 may include any other suitable optical component (not shown) known in the art.

The inspection system shown in FIG. 3B is configured to detect the regularly reflected light from the wafer 322, and the inspection system 305 is configured with a BF inspection system. However, this inspection system 305 can also be configured for other types of wafer inspection. For example, the inspection system shown in FIG. 3B may include one or more other channels (not shown). Other channel (s) may include any optical components disclosed herein, such as a lens and a detector configured as a scattered light channel. The lens and detector may also be configured as disclosed herein. In this manner, inspection system 305 may be configured for DF inspection.

The inspection system 305 may include a computer system 310 configured to perform one or more steps of the methods disclosed herein. For example, the optical element described above may form the optical subsystem 311 of the inspection subsystem 305, which may include a computer system 310 coupled to the optical subsystem 311. In this manner, the output generated by the detector (s) during scanning can be provided to the computer system 310. [ For example, when the computer system 310 receives an output generated by the detector (e.g., by one or more transmission media, shown in phantom in Figure 3B, which may include any suitable transmission medium known in the art) The computer system 310 may be coupled to the detector 312. [

The computer system 310 of the inspection system 305 may be configured to perform any of the operations described herein. For example, computer system 310 may be configured to perform defect detection as described herein. In addition, the computer system 310 may be configured to perform any of the other steps described herein. Further, some of the operations described herein may be performed by different computer systems, but all of the operations of the method may be performed by a single computer system, such as the inspection system 305 or an independent computer system. In addition, one or more of the computer system (s) may be configured as a virtual tester, such as that described in U.S. Patent No. 8,126,255, issued Feb. 28, 2012 to Bhaskar et al. ≪ / RTI >

May be included in another tool, such as the EDA tool 306 described above, so that the computer system 310 can receive the output generated by the computer system 308, which may include a design generated by the computer system 308 The computer system 310 of the inspection system 305 may be coupled to another computer system that is not part of an inspection system, such as a computer system 308, For example, two computer systems may be effectively connected by a shared computer-readable storage medium, such as a fab data record, or may be connected by a transmission medium as described above such that information may be transferred between the two computer systems. have.

3b provided herein is intended to generally illustrate the configuration of a test system that may be included in the system embodiments disclosed herein. Obviously, the inspection system configuration described herein can be modified to optimize the performance of inspection systems that are normally performed when designing a commercial inspection system. In addition, the system described herein may be implemented using an existing inspection system, such as the 29xx / 28xx series of tools commercially available from KLA-Tencor (for example, ). ≪ / RTI > For some such systems, the methods described herein may be provided as optional features of the system (e.g., in addition to other functions of the system). Alternatively, the system described herein may be designed "from scratch" to provide a completely new system.

4 illustrates a fabricated device with consistent modulation between a target component and a reference component, according to an embodiment. As shown, the fabricated device includes a plurality of column sets 402A-D having respective central columns 404A-D of the target component. The fabricated device also includes two columns 406A-D, 408A-D adjacent to each set of fine central columns 404A-D with a reference component for the target component. The target component and the reference component of the fabricated device have a similar pattern. In addition, the target and reference components in each row of each of the column sets 402A-D have consistent modulation (e.g., +4, +3, etc.) and form a modulation set. As also shown, each modulation set has a different modulation.

Thus, defect detection for the pattern can be performed separately for each modulation set, which eliminates differences that occur when comparing the nominal reference component to the modulated target component. For example, if the fabricated device is a wafer, target components and reference components in the modulation set become separate dies with the same pattern located on the wafer, so that defects can be detected on the target die. Exemplary embodiments of such defect detection are described in further detail below with reference to sequential figures.

Although each column of target components 404A-D is shown as being located on either side with adjacent columns of the reference components 406A-D, 408A-D, the manufactured component may be configured to have a different layout in other embodiments For example, the target component 404A-D does not need to be located between the columns of the reference components 406A-D, 408A-D and / or the reference components 406A-D, 408A- The columns may be configured so that they do not need to be adjacent to the columns of target components 404A-D. It should also be noted that while FIG. 4 shows multiple sets of modulation in each of multiple column sets 402A-D, the fabricated device need not be limited to having multiple modulation sets. However, in order to maximize data collection for defect detection (described below) using the fabricated device, by configuring the fabricated device to have multiple column sets 402A-D, as shown, for example, The available space on the device can be utilized.

In particular, in a simplified embodiment (not shown), the fabricated device includes a single modulation set, a target component with a first modulation, and at least two reference components for a target component comprising a first reference component and a second reference component And the first reference component and the second reference component each have a first modulation. Such a modulation set may have any of the configurations described above.

In the context of this disclosure, the modulation may be any amplification (positive or negative) of one or more parameters of the target component and the reference component. Thus, the modulation may be exposure, focus, etc., or any combination thereof. By way of example only, within each modulation set, the modulation applied to it may include a combination of a specific exposure value and a specific focus value. U.S. Pat. Patent No. No. 8,213,704 discloses a technique for modulating the components of a manufactured device.

Figure 5 illustrates a method 500 for comparing a reference component with a target component that has been consistently modulated for defect detection, in accordance with an embodiment. The consistently modulated target and reference components may be located on a manufactured component as described above with reference to FIG. The descriptions and regulations provided above can be equally applied to this embodiment.

As shown in operation 502, a first image of a target component of the fabricated device is received, and the target component has a first modulation. The first image may be received from a collector of the inspection system. Also, at operation 504, a second image of a first reference component of the fabricated device for the target component is received (e.g., from a collector), and the first reference component has a first modulation. Also, at operation 506, a third image of a second reference component of the fabricated device for the target component is received (e.g., from a collector), and the second reference component has a first modulation. In this embodiment, the target component, the first reference component, and the second reference component may be located in the modulation set on the fabricated device.

Also, at operation 508, a first comparison of the first image and the second image is performed to produce a first result indicative of the difference between the first image and the second image. A comparison may be performed by the inspection system and / or the processor of the individual computer system. At operation 510, a second comparison of the first image and the third image is performed (e.g., by the processor) to produce a second result indicative of the difference between the first image and the third image. Also, at operation 512, a third comparison between the first and second results is performed (e.g., by the processor) to detect defects in the target component.

In an embodiment, comparing the first result to the second result to detect defects in the target component comprises determining from a comparison difference between the first result and the second result (e.g., in the difference image) And detecting each determined difference (e.g., each item in the difference image) as a defect in the target component. Thus, the similarity between the first and second results may not need to be recognized as a defect in the target component. In other words, each determined difference may indicate that the location on the target component corresponding to the location of the determined difference on the difference image is a defect in the fabricated device.

By using a consistently modulated target component and a reference component (e.g., in a modulation set) to detect a defect, the difference (as disclosed with respect to the prior art) obtained only from modulating the target component can be eliminated . This can enable more accurate detection of actual defects by eliminating false-positive detection. In particular, the defect location can be more accurately identified due to the concentrated difference image.

Optionally, a defect in the target component may be detected based on a predefined threshold applied to a third comparison of the first result and the second result. The predefined threshold may be a difference threshold that must be met to ensure that the defect is ultimately detected at that location so that the first location and the corresponding location on the second result are considered to be different. In other words, if the first and second results are sufficiently different at any particular location determined using a predefined threshold, the corresponding location on the target component may be determined to be defective.

If a consistently modulated target component and a reference component are used in the modulation set, the predefined threshold can be reduced as a result of the lack of false positive detection from the results of the prior art modulating only the target component. For example, a larger threshold is typically required in the prior art to account for potential false positive defect detection. Also, since the reference component and the target components in the modulation set are similar patterns with the same modulation, they can have similar background noise levels, allowing smaller thresholds to be used. The reduced threshold value of the above-described embodiment allows the inspection to be more sensitive and to detect smaller defects.

Figure 6 illustrates a detected defect that is gradually removed in an increased modulation, in accordance with an embodiment. In an embodiment, the method 500 described in FIG. 5 may be performed for each of a plurality of target components of a fabricated device having a similar pattern and having different modulation for detecting defects in the pattern. For example, the method 500 may be repeated for each of the modulation sets shown in FIG. As another option, the additional modulation set may span one or more fabricated devices in a manner similar to that shown in FIG. 4, but may be positioned for different modulation, so that the method 500 may be implemented with a modulation set ≪ / RTI >

As shown in Fig. 6, at the lower modulation of the pattern, fewer defects are detected. This occurs because the difference between the target component and the reference component is less visible due to the small amplification of the pattern in the target component and the reference component. As the modulation of the pattern increases, the number of detected defects may also increase. In other words, this is because the difference between the target component and the reference component is more visible as the amplification becomes larger. However, if an image for higher modulation indicates that the position previously identified as having a difference can be identified as currently similar, then the detected defect in the lower modulation can be eliminated. In this way, some of the defects detected for the pattern can be gradually removed when the method 500 of FIG. 5 is repeated for each incremental modulation. As a result, the number of defects can be automatically corrected by the inspection system. However, some of the detected defects in low modulation can still be identified in high modulation if they are systematic and spatially random.

In addition, the thresholds used as thresholds for identifying the predefined thresholds, i.e. differences representing defects discussed above with respect to FIG. 5, are the same for each instance of the method 500 performed for the various modulation sets . The use of the same predefined threshold may be possible as a result of consistent modulation across the components of each modulation set.

Figure 7 illustrates statistics generated as a function of the number of defects detected in a pattern for different modulation, according to an embodiment. As shown, to some extent, the number of defects detected in the pattern may increase as the modulation increases. However, as described above, defects detected at lower modulations can be eliminated at higher modulations, so that the number of detected defects can plateau and decrease as the modulation at any point increases. Thus, the statistics can indicate a curve that maximizes the number of detected defects. The modulation associated with this point can be identified as being optimal for detecting defects in the fabricated device. Identifying the optimal modulation for a particular pattern allows future wafers to be properly fabricated with sufficient modulation to cover the die dominated by random defects. In addition, increasing modulation can stabilize defects due to systematic defects by each critical pattern type.

While a number of embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. Accordingly, the breadth and scope of the preferred embodiments should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims (21)

In the manufactured device,
A target component having a first modulation; And
At least two reference components for the target component, each first reference component having a first modulation and a second reference component,
/ RTI > The method according to claim 1,
Wherein the fabricated device is a wafer. 3. The method of claim 2,
Wherein the target component and the at least two reference components are individual dies with similar patterns located on the wafer or are racquets. The method according to claim 1,
Wherein the first modulation comprises a combination of a specific exposure value and a particular focus value. The method according to claim 1,
Further comprising a plurality of additional target components each having a similar pattern for the target component and each having a different modulation. 6. The method of claim 5,
Further comprising at least two additional reference components comprising a first additional reference component and a second additional reference component for each of the additional target components to form a modulation set,
Wherein the at least two additional reference components in the modulation set have a similar pattern for the additional target component and have the same modulation as the additional target component in the modulation set. The method according to claim 6,
Wherein the target component and each of the plurality of additional target components are located in a single first column of the manufactured device and wherein the first reference component and each of the first additional reference components comprise a single Wherein the second reference component and each of the second additional reference components are located in a single third column of the fabricated device. 8. The method of claim 7,
Wherein the first column is positioned between the second column and the third column. 8. The method of claim 7,
Wherein the first, second, and third columns are adjacent to each other. In the method,
Receiving a first image of a manufactured device of a target component having a first modulation;
Receiving a second image of the fabricated device for the target component, the second image of a first reference component having the first modulation;
Receiving a third image of the fabricated device for the target component, the third image of a second reference component having the first modulation;
Performing a first comparison of the first image and the second image to produce a first result indicative of a difference between the first image and the second image;
Performing a second comparison of the first image and the third image to produce a second result indicative of a difference between the first image and the third image; And
Performing a third comparison between the first result and the second result to detect a defect in the target component
/ RTI > 11. The method of claim 10,
Wherein the first, second, and third images are received from a collector of the inspection system. 12. The method of claim 11,
Wherein the first comparison, the second comparison, and the third comparison are performed by a processor of the inspection system. 11. The method of claim 10,
Wherein comparing the first result to the second result to detect a defect in the target component comprises:
Determining from a comparison difference between the first result and the second result; And
Detecting each determined difference as a defect in the target component
≪ / RTI > 14. The method of claim 13,
Wherein the similarity between the first result and the second result is not identified as a defect in the target component. 11. The method of claim 10,
Wherein detecting a defect in the target component is based on a predefined threshold applied to the third comparison. 11. The method of claim 10,
Wherein the method is performed for each of a plurality of target components of a fabricated device having a similar pattern and different modulation to detect defects in the pattern. 17. The method of claim 16,
When the detected defect is determined from a high modulation that is related to the similarity between the first result and the second result, the defect detected for the similar pattern as the method is repeated for each incremental modulation, ≪ / RTI > 17. The method of claim 16,
Wherein the same predefined threshold is applied to each third comparison repeated for the different modulation to detect defects in the pattern. 17. The method of claim 16,
Wherein statistics are formed as a function of the number of defects detected in the pattern for each of the different modulations and wherein the statistics are used to identify optimal modulation to detect defects. A computer program product embodied in a non-transitory computer readable medium,
The computer program product comprising:
Receiving a first image of a manufactured device of a target component having a first modulation;
Receiving a second image of the fabricated device for the target component, the second image of a first reference component having the first modulation;
Receiving a third image of the fabricated device for the target component, the third image of a second reference component having the first modulation;
Performing a first comparison of the first image and the second image to produce a first result indicative of a difference between the first image and the second image;
Performing a second comparison of the first image and the third image to produce a second result indicative of a difference between the first image and the third image; And
Performing a third comparison between the first result and the second result to detect a defect in the target component
The code being configured to be executed by a processor to perform a method comprising: In the inspection system,
Collector; And
Processor
Lt; / RTI >
The collector
Collecting a first image of a manufactured device, a first image of a target component having a first modulation,
To acquire a second image of the manufactured device for the target component, a second image of a first reference component having the first modulation,
To acquire a third image of a second reference component having the first modulation of the manufactured device for the target component
Respectively,
The processor comprising:
Performing a first comparison of the first image and the second image to produce a first result indicative of a difference between the first image and the second image,
Performing a second comparison of the first image and the third image to produce a second result indicative of a difference between the first image and the third image,
To perform a third comparison between the first result and the second result to detect a defect in the target component
Wherein the inspection system comprises:

Images